Just on this particular vehicle, I didn't read or at least couldnt find any reference to the seller keeping the cabin and flogging off the rest for "hot rodding or rat rodding!" If the full add says otherwise, IDSTBC
Perhaps it may be something as simple as he had bought a second unit needing only a cabin to rebuild and all else is surplus?
I did exactly that and IF ever I finish, I'll have no hesitation in jettisoning off all the extras.
I know there are purists, seen many examples here on this forum, "rivet counters" who would search patiently for a correct part to turn up and then drive halfway across the country to obtain it.
Seen blokes also on here go the other extreme, stuffing all sorts of engines into vehicles.
To each his own, I say!
Do whatever you like, as long as it fits within whats acceptable with the licensing authorities.
Dave_64